FIG. 1 shows a known fuel injector from the related art, which has a classical three-part construction of an inner metallic flow guidance part and a housing component at the same time. This inner valve pipe is formed by an intake nipple forming an inner pole, a nonmetallic intermediate part and a valve-seat support accommodating a valve seat. In the valve-seat support there is situated an axially movable valve needle, which includes an armature and a ball-shaped valve-closure member, as well as a connecting pipe connecting the armature to the valve-closure member. The three individual components of the valve needle are solidly connected to one another, using a continuous material jointing method, especially welding.
Such an electromagnetically operable valve in the form of a fuel injector is discussed in DE 40 08 675 A1. The inner valve pipe forms the skeleton of the entire injector and overall has a substantial supporting function from the three individual components. The nonmagnetic intermediate part is connected by welding seams both tightly and solidly to the intake nipple as well as to the valve-seat support. The windings of a magnetic coil (solenoid) are inserted into a spool holder of plastic which, in turn, surrounds a part of the intake nipple used as the inner pole and also the intermediate part, in the circumferential direction. In the valve-seat support there is situated an axially movable valve needle, which includes a sleeve-shaped armature and a ball-shaped valve-closure member, as well as a connecting pipe connecting the armature to the valve-closure member. The connecting pipe is connected solidly to the armature and also to the valve-closure member by welding seams. The valve-closure member cooperates with a frustoconical valve seat surface of a metallic valve seat member. The valve-seat member is solidly connected to the valve-seat support by a welding seam.
A further electromagnetically operable valve in the form of a fuel injector is discussed in DE 195 03 224 A1. The fuel injector has a ball-shaped valve-closure member collaborating with a valve seat which is mounted at a closure-member support in the form of a plastic pipe, while at the end lying opposite to the valve-closure member, an armature is fastened to the plastic pipe. Together, these components form an axially movable valve needle. The lower end of the plastic pipe is dome-shaped, in the dome-shaped recess, the valve-closure member being held in place with form locking, using a snap-fit connection. The plastic pipe is developed in a springy manner in the area of the lower recess, since holding jaws have to encompass the valve-closure member. The ball-shaped valve-closure member may be made of steel, a ceramic or a plastic. The valve-closure member collaborates with a frustoconical valve-seat surface of a metallic valve-seat member. The valve-seat member is solidly connected to the valve-seat support by a welding seam.